MacArthur Genius Searching for Signs of Life on Exoplanets

Could E.T. be trying to phone home? It's not so far-fetched, says Sara Seager.

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Sarah Seager is one of 24 winners of the 2013 MacArthur Fellowship, or genius grant.

Photograph courtesy John D. and Catherine T. MacArthur Foundation

"This year's class of MacArthur Fellows is an extraordinary group of individuals who collectively reflect the breadth and depth of American creativity," said Cecilia Conrad, vice president of the MacArthur Fellows program, in a press release announcing the 2013 recipients on Wednesday. "Their stories should inspire."

"Exoplanets are planets that orbit stars other than the sun," Seager explained. "I study exoplanet atmospheres to model how they will look and try to interpret data to understand these atmospheres."

The search for exoplanets has ramped up recently, although the search for them has been going on for years. The problem? Think about the stars you see in the sky. Littered among those stars are exoplanets—none of which you can see because they are quite literally outshined.

"Exoplanets are so faint compared to their stars," Seager said.

It's like trying to spot a tiny prick of light next to a flood light. The technology to hunt for them became good enough only in the last 20 years.

"The star is a huge problem" because it is so bright, Seager said. "All the techniques are indirect. We have to look for the star first to find planets. Big planets are easier to find than small planets."

Finding an Earth Twin

Exoplanets have been instrumental in understanding the potential for life on other planets, Seager said. Understanding what their atmospheres are made of gives us clues to whether the planets could support life.

It's all about the biosignatures—the gases that make up these atmospheres. Biosignatures are gases like oxygen, methane, and carbon dioxide thought to be produced by life forms.

If researchers like Seager can figure out what kinds of gases swirl around the atmospheres of distant worlds, they could potentially pick up the signatures of extraterrestrial life. In other words—Earth's twin.